CODEWITHSUNDEEP
c#synchronizationlockingui-thread
digital_fate
digital_fate

Reputation: 597

Synchronise access to a resource from the UI thread

I lock on a global object in order to synchronise communication to an external device from various threads, which is working fine.

I want to user a slider control to set values which I then send to my external device, so I'm using its Scroll event to listen for changes before sending them off to the device.

The problem is, I need to lock on the global object before communicating with the device, as follows:

private void slider_Scroll(object sender, EventArgs e)
{
    lock(lockObject)
    {
        //send slider values to external device
    }
}

The above always hangs indefinitely on attempting to gain the lock. The rest of my code has been working fine, so I don't think I have a genuine race condition - I'm assuming this is happening because it's running on the UI thread and that it's a Bad Idea to block on the UI thread? I could be wrong.

However, if this is the case, I'm guessing I need to wrap the above code in a method and somehow invoke it on the 'main' thread from the UI thread?

How can I achieve this?

Upvotes: 0

Views: 79

Answers (1)

Idle_Mind
Idle_Mind

Reputation: 39132

Definitely never a good idea to use lock from the main UI thread. Add a BackgroundWorker() control to the form and pass the slider value into the RunWorkerAsync() method. You can retrieve the value in the DoWork() handler via e.Argument, and safely use lock from there.

Upvotes: 1

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